Core B. Tissue Acquisition, Processing, and Pathology (TAPP) Core In order to successfully achieve the overall goal of this Program Project, that is, moving CAR T cell therapy to solid tumors, an integrated approach is needed. A key component will be the analysis of the infused CAR T cells and the tumor tissues. The overall goal of Core B is to serve as the entity that will collect and process clinical trial specimens provided by Project 1, conduct some of the basic biocorrelate studies, and provide a centralized structure for immunohistochemical analysis of tissue specimens from the clinical trial and from preclinical studies. The specific tasks of Core B will include: 1) processing, archiving, and distributing clinical specimens (to Project 3) from ongoing and planned clinical trials from Project 1, 2) performing basic CAR T cell biocorrelate assays including blood cytokine analysis, measurement of serum tumor biomarkers, and the persistence of CAR T cells in peripheral blood and other compartments, 3) Analyzing immune responses against the infused CAR T cells, 4) measuring anti-tumor immune responses generated by CAR T cells, 5) reviewing and analyzing pathologic specimens from clinical trial patients (Project 1), including expression of mesothelin levels, FAP levels, and potentially other tumor antigens, as well as interpretation of tumor biopsies, and 6) assisting in the immunohistochemical analyses needed in Projects 2 and 3. Dr. Jos Melenhorst will be the Director of the TAPP Core. He will be assisted by Dr. Simon Lacey. Dr. Leslie Litzky, a Board-Certified Anatomic Pathologist, will be the other Co-Core Leader and the designated reference pathologist who will supervise Aims 5 and 6.